Manufacture of metallic illuminating bodies for electric incandescent lamps.



'EUGEN ntmwrrz or 11mm.

GENERAL ELECTRIC COMPANY,

GEmrmY;

A conronnrron or NEW YORK.

ASSIGNOR. BY MESNE ASSIGNMENTS, TO

MANUFACTURE or METALLIC runnmarme fihmns R ELECTRIC monunsscnur Patented June 9, 1914.

LAMPS. .F

ll .099.304. Specification of Letters Patent.

No Drawing.

Application filed October 16, 1306. Serial No. 339,165.

'1 '0 all whom it may com-cm 7 Be it known that I, Enos l-Iuuwrrz, a subject of the German Emperor. and a rcsident of Alte Jakohstrasse 139, Berlin, Germany, have ll lvcll'feil certain new and useful Improvements in the Manufacture of ll-letallic Illuminating Bodies for Electric Iu--- A candescent Lamps; and I do hereby declare j filament not heretofore the following to be a full, clear, and exact description of the invention such as will enable others skilled in the mm which it appertai-ns to make and use the same.

' My invention relates to an improved proci ess for the manufacture of metallic illumina ting bodies for electric incandescentlamps, said'processresulting in a superior produced.

In the manufacture of illuminating bodies from tungsten, by subjecting raw filaments cemented together from finely divided particles to a sintering process very strong con traction takes place. This contraction im- 5 mediately shortens the length of the final metallic filament as compared with the raw 1 filament and does not always take place uniformly, and the resistances of the illuminat- 1 ing bodies consequently fluctuate within certain limits. It has been found that this shriveling process proceeds more uniformly if the filaments treated be subjected to a gentle pull or put under slight tension during the process by which they are caused to shrivel up. Means for eflecting this pull or tension, loading of a stirrup or loop shaped filament by a small weight attached to the stirrup or loop, are known of themselves and have been used for the purpose of drawing out filaments already finished into a pointed form.

i for the formation of ellccted, as well as a saving The new process consists in acting upon or loading the raw filament while in the process of manufacture. By this means several advantages are secured. Firstly the disadvantage of irregular contraction already mentioned is avoided, the filament bcing characterized by a uniformity of contraction which results from the tension upon 5 it while its particles are sintered and shrunk together. .lllorcover the straight portions of the filament-will be perfectly straight and the filament will present a similar evenness throughout. Filaments which have been ful y sintered and finished without a load i cannot be entirely freed from irregularities l 7 and kinks by subsequent tension treatment as above referred to, no matter how highly they may be incandescent so that my new prm-ess gives to the filament characteristics of evenness by which it mayreadily be dis tinguisheil from filaments of a similar nature produced in any other known manner. In addition to this a considerable commercial advantage is attained inasmuch as a simplification of the manipulations required the finished filament is in the plant required, in so far as the drawing of the filament into a pointed formdoes not necessilate a second operation in the case of filaments of this said pointed hair pin loop 5 form the advantages of my invention are specially pronounced. Finally the number of defective and unserviceablc filaments produccd is materially lessened, as filaments which would be deformed during the sintering process in consequence of deficient quality or careless handling, without being loaded, yield when loaded serviceable finished filaments. v p

The process consists therefore broadly in subjecting the raw filaments consisting of metallic particles Whileacted upon by a load to that process which turns them into finished filaments.- so that the chemical and physical actions which convert the filament to its final shape will take place while such filament is under the expanding or stretching action of the load. The load may consist of a small weight of any desired kind, conveniently of a small hook of metallie tungsten. This small weight or hook is hung within the loop of the raw filament and its gravity exerts a tension in a direction away from thepoints of support for the raw filament. These raw filaments, being composed as above described of finely divided particles of tungsten cemented together, are, of course, filaments incapable of use as incandescent filaments, being composed of fine tungsten particles and cementin material. its physical inake-up is composite and not uniform. If this raw filament is imagined to consist of a series of suc cessive particles of tungsten, cement, etc, it becomes apparent that the small weight would break the filament if the cement were removed atany one point. As the electric current passes through this raw filament, it

--tallic filament far shorter in length" than the causes the removal of the cementing means I wlthout, however, breaking the continuity of the thread. The Weight of the hook is, of I course, so figured that it will not of its own Weight and by more force of weight break through the filament. The weight of the hook is1reli d upon to exercise a tension\ away from the points of support of the'filal ment so that it assists in performing the unique function of producing a properly formed filament by a pull againstthe filament which results paradoxically in a me-i raw filament, and in spite of the pull or tension of the hook in a direction away from the points of support, it isnearer the points of support of the filament at the end of the process than at the beginning.

Having thus described my invention, What I claim as new therein and desire to secure by Letters Patent of the United States of America is:

1.- The process for the manufacture of illuminating filaments of tungsten which 1 consists in loading a very thin thread-like g agglomeration of tungsten and carbon While in a very tender and brittle state in such a cles durin cles during the Way that tension would be exerted upon said thread-like body in a direction away from its points of support and effecting the con- 1 version of said raw agglomerated body into a finished metallic filament during the time that'said load exercises eiiective tension upon the filamentary body. v 1

2. The method for the manufacture of fili aments consisting of fine metallic particles sintered together Which consists in subjecting raw filaments to treatment whereby the particles of the final filaments are sintered and shrunk together while the filaments are under tension.

'3. The niethod which consists in subjecting raw filaments consisting of finely divided metallic particles sintered together to treatment whereby the cementing means is eliminated and the particles of the final material of the filament are sintered together While the filament is under tension.

4. An incandescent filamentary body con sisting of particles of metallic tungsten uniformly sintered together by application of tension to the agglomerated metallic partithe sintering operation into a coherent fi ament even throughout its length and perfectly straight except Where definitely bent.

5. An incandescent body consisting of particles of metallic .-tungsten uniformly.

sintered and shrunk together by ap lication of tension to the agglomerated metal ic parti sintering operation into an even filament of loop shape having a sharp bend and straight even legs.

In testimony, that I claim the foregoing as my invention, I have signed my name in presence of two subscribingwitnesses.

EUGEN HURWITZ. Witnesses:

HENRY HASPER,

WOLDEMAN HAUPT. 

